T. Satyanarayana and Kaushik Majumdar. International Plant .... wheat. Biotechnology, breeding, ... Figure 3 â Decadal trends in maize productivity in India during 1950-2011. P ro d u c tiv ity. (k g. /h a. ) ...... Manual: A Manual for Improving the.
Indian J. Fert., Vol. 9 (4), pp.80-94 (15 pages)
Fertiliser Best Management Practices for Maize Systems M. L. Jat International Maize and Wheat Improvement Centre (CIMMYT), NASC Complex, Pusa, New Delhi
T. Satyanarayana and Kaushik Majumdar International Plant Nutrition Institute (IPNI), South Asia Program, Gurgaon, Haryana
C. M. Parihar and S. L. Jat Directorate of Maize Research, Pusa, New Delhi
J. P. Tetarwal Maharana Pratap University of Agriculture and Technology, ARS, Kota, Rajasthan
R. K. Jat Borlaug Institute for South Asia (BISA)-CIMMYT-India, Pusa, Bihar
and Y. S. Saharawat Indian Agricultural Research Institute (IARI), Pusa, New Delhi
Maize is an important crop for food and nutritional security in India. Strong market demand and resilience of maize to abiotic and biotic stresses have increased the area and production of maize in the country over the past decade. Productivity of maize, however, has not increased proportionately and significant yield gaps are evident across maize growing areas in the country. Maize is an exhaustive crop and removes large amounts of plant nutrients from the soil to support high biomass production. The 4R Principles of applying right source of nutrients, at the right rate, at the right time and at the right place is expected to increase nutrient use efficiency, productivity and farm profit from maize production and provides opportunity for better environmental stewardship of nutrients. Adaptation of 4R Principle-based site-specific nutrient management decision support tools provides the opportunity for large-scale adoption of improved nutrient management across maize ecologies.
M
aize, a crop of worldwide economic importance, provides approximately 30% of the food calories to more than 4.5 billion people in 94 developing countries. The demand for maize is expected to double worldwide by 2050. Maize is considered as the third most important food crop among the cereals in India and contributes to nearly 9% of the national food basket (7). Grown in an area of 8.55 mha with an average productivity of 2.5 t ha -1 , maize contributes to more than half of the coarse cereal production of the country. The annual maize production in India is about 21.7
80
mt with an annual growth rate of 3 to 4 % (1). Maize yields in India need to be increased significantly to sustain this growth rate to meet India’s growing food, feed and industrial needs. Area, production and productivity of maize grew impressively during XIth plan at a growth rate of 2.6, 8.2 and 4.9%, as a result of commendable response both from the producers and industries (12). Historically, the area, production and productivity growth of maize during pre-green revolution era (upto 1970) was in increasing order but it remained slow and static during for almost 2 decades of post-
green revolution era. However, during past one decade (20032011), there has been quantum increase in area, production and productivity of maize in India (Figures 1, 2 and 3). Introduction of single cross hybrids in Indian maize programme since 2006 resulted in productivity enhancement of 134 kg ha - 1 annum -1 in the last five years although the extent of coverage was less than 25%. Growing market demand by the feed and starch industry and increase in minimum support price from Rs. 540 q-1 in 2006-07 to Rs. 1175 q-1 in 2012-13 led to make maize as a more competitive crop and
Indian Journal of Fertilisers, April 2013
Figure 1 – Decadal trends in maize area in India during 1950-2011
encouraged farmers to grow maize to a large extent. Also, the export competitiveness of Indian maize especially for East Asian economies due to low freight charges made this crop more versatile with no carryover stocks and India exported a record 4.6 mt of maize during 2012-13 (12) and further opens the avenues for more
demand of maize in India. Consequently, maize is rapidly emerging as a favourable component crop in the major cereal based cropping systems of India. Development of high yielding maize hybrids with lesser water requirement, resilience to biotic and abiotic stresses, high resource
use efficiency under various agroclimatic conditions, have led to development of new maize based cropping systems adapted to various farm typologies. With the current and projected challenges for natural resources such as water scarcity, temperature stresses etc, maize has emerged as a potential alternative for
Figure 2 – Decadal trends in maize production in India during 1950-2011
Indian Journal of Fertilisers, April 2013
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Productivity (kg/ha)
Figure 3 –
Decadal trends in maize productivity in India during 1950-2011
diversification of rice-rice system with rice-maize and maize-rice systems; and rice-wheat system with rice-maize cropping systems in many ecologies of the country. Also, the market driven agriculture of specialty corn in peri-urban interface has opened another avenue for diversifying intensive cereal systems (13). Highyielding maize hybrids, with very high biomass production, extracts higher amounts of mineral nutrients from the soil than by other major cereals like rice or wheat. Biotechnology, breeding, and agronomic advancements have propelled maize yields to new highs with little guidance about fertilisation strategies for these modern maize hybrids to achieve their maximum yield potential. Being an emerging crop in many non-traditional ecologies and seasons, grown under different cropping systems and management practices, there exist large information gap on appropriate nutrient management strategies for maize in contrasting cropping systems and management practices. The 82
fertiliser best management practices (FBMPs) for maize under such scenarios are still not well developed to help realize the sustainable benefit of these alternative maize based cropping systems. Application of existing fertilisation practices, developed decades ago, may not match uptake requirements of modern hybrids that are now grown at population densities higher than ever before. Nutrient requirement of maize varies from field to field due to high variability in soil fertility across farmer fields, and single homogenous nutrient recommendations may not be very useful in improving maize yields. Increasing fertiliser prices and escalating fuel prices in international market will make fertiliser input one of the costliest in agriculture. Fertiliser best management practices, with due importance to indigenous sources of nutrients such as organic manures, biofertilisers, crop residues, inclusion of legumes, use of nutrient efficient genotypes etc., will be required for sustainable management of emerging maize
systems in the country. This paper provides a synthesis of current information on maize production systems, pros and cons of existing nutrient management strategies and the fertiliser best management practices for bridging yield gaps in current and emerging maize systems in the country. Maize-based Cropping Systems in India Maize is a versatile crop adapted to range of ecologies, seasons and regions in the country, and is grown in sequence or as companion crop with a range of crops under different production systems. However, the geographical spread of different maize-based rotations varies primarily with adaptability for a cropping window under prevailing ecology, land topography, soil type, moisture availability, and markets. Traditionally being a monsoon season crop, maize-wheat is still the predominant maize based system (1.8 mha) and is 3rd major crop-rotation in India and contributes ~3.0 % in national food Indian Journal of Fertilisers, April 2013
basket. The other major maizebased systems are maize-fallow, maize-mustard, maize-chickpea, maize-maize, maize-potato, etc. In recent past, the challenges of water shortages, temperature stresses in rice primarily in rice systems and to some extent in wheat systems, and opportunities of higher productivity of maize under these constrained environments as well as market opportunities for maize have led to evolution of several maize systems in non-traditional maize ecologies. For example rice-maize (~0.5 mha) has emerged as a potential maize system replacing winter rice in water scarce areas of double rice ecologies and wheat in terminal heat prone shorter wheat season ecologies. Introduction of high yielding maize hybrids for spring season and its adaptability to intensive rice systems have also led to evolution of rice-potatomaize system in larger areas of IGP. Emerging challenges of water scarcity and availability of very high yield potential hybrids for monsoon season coupled with improved agronomic management practices are leading to opportunities for re-evolution of maize-wheat-mungbean rotation in non-traditional intensive rice-wheat systems in western Indo-Gangetic Plains (IGP). Also, the emerging market opportunities for specialty corn and green cobs, high value intercropping systems involving maize are also emerging as potential maize systems in periurban regions of the country. Yield Gaps in Maize Fundamentally, yield gaps are caused by deficiencies in the biophysical crop growth environment that are not addressed by agricultural management practices. Yield potential (Yp) of any crop cultivar/ hybrid for a site and for a given planting date is the yield achieved when grown in environments to Indian Journal of Fertilisers, April 2013
which it is adapted, with nutrients and water non-limiting and pests and diseases effectively controlled (10). Timsina et al. (37) using hybrid maize models, estimated yield potential of four maize hybrids in India that ranged from 7.1 to 19.7 t ha -1 and reported that planting during August to November gave exceptionally high yields due to low temperature during grain filling, long growth duration, and large receipts of solar radiation at some of the locations. Attainable yield (Yat), generally set at 80–90% of Yp, is average grain yield in farmers’ fields with best management practices and without major limitations of water and nutrients. Attainable yield can be limited by variety, planting density, water and nutrient management, soil-related constraints (acidity, alkalinity, salinity, etc.), and climate-related constraints (flooding, drought, etc.). Actual yield (Yac) is the yield farmers receive with their average management under all possible constraints. The difference between attainable yield (Yat) and actual yield (Yac) of crop species and varieties can be quite large. Attainable yield of maize in farmers’ fields, achieved under optimal conditions, can vary significantly across the agroecologies mainly due to genotype x environment interactions but also due to confounding influence of biotic and abiotic stresses and agronomic management. Dass et al. (6) reported Yat and Yac of maize from experiments conducted in 13 representative locations in various agro-environments for 9 years (1995–2003) under the All India Coordinated Research Project (AICRPM) on maize. The selected locations were first divided into two categories: locations having lower productivity than the national average (Banswara, Udaipur, Godhra, Varanasi, Kanpur and Chhindwara) and locations (Mandya, Arbhavi, Ludhiana, Dhaulakuan, Bajaura, Dholi and Hyderabad) with greater
productivity as compared to national average. Data indicated that the Yac is always less than Yat under all the agro-environments due to limited availability of agronomic inputs and their scheduling. Potential for improving Yat was more at the locations of the first group as compared to the locations of the second group. Except Banswara, other locations of the first group showed the potential for achieving Yat of 4–6 t ha-1, while Yac at all the locations of this group was less than half (1-2 t ha-1 ) of the Yat. It has also been reported that present average Yac at farmers’ fields is only about 50% of the Yat, which could be increased through adoption of improved technology. On the other hand, Yat for most locations was about 4.0 t ha - 1 except for Arbhavi (5.9 t ha-1) in the high productivity group, whereas, Yac at most of the locations of this group was more (1.2–3.4 t ha-1 ) as compared to the low productivity group (6). The data reveal that Yat of maize can be quite large, and so yield gap between Yp and Yat, between Yat and Yac, and that between Yp and Yac can be minimized. Systematic analysis of the role of general and location specific determinants of maize yields may help to narrow down the yield gap at various levels and improving actual yields. Potential, attainable and actual yields of maize were evaluated at seven representative locations in South Asia under various agro-environments to generate the productivity scenario of maize under these ecolologies. The analysis of the simulated, attainable and actual maize yields in major maize growing ecologies across South Asia (Figure 4) revealed wide ‘management yield gaps’ ranging from 36 to 77% (30). These gaps are ascribed mainly to three major factors, (i) low yielding genotypes, (ii) poor crop establishment due to random broadcasting and (iii) inadequate and inappropriate fertiliser 83
nutrient applications as 15-45% maize acreage remains unfertilised and the rest of the acreage has imbalanced nutrient applications (6, 15). Nutrient Use in Maize Nutrient removal is far excess of their replenishment under intensively cropped cereal systems in India, which has led to widespread multi-nutrient deficiencies in soils, consistently increasing response of crops to nutrient application (21). As a result of improved agronomic, breeding, and biotechnological advancements in maize systems, yields have reached far higher levels than achieved ever before. However, greater yields of maize have always been accompanied by a significant removal of macro and micronutrient from the soil. The latest summary on soil test levels in North America by IPNI reported that an increasing percentage of U.S. and Canadian soils have dropped to levels near or below critical P, K, S, and Zn thresholds during the last 5 years (11). Soils with decreasing fertility levels, coupled with higher yielding
hybrids, suggest that farmers have not sufficiently matched nutrient uptake and removal with accurate maintenance fertiliser applications. Timsina and Majumdar (36) indicated that maize grain yields in Bangladesh have been decreasing where maize was grown on the same land for the last 5 to 10 years. The authors attributed the yield decline to imbalanced and inadequate nutrient application by farmers. Maize with the yield potential of less than one t/ha removes about 90-100 kg/ha of nutrients from the soil (Table 1). With the introduction of improved cultivars, the productivity has increased up to 4.0 t/ha with nutrient removal of around 220 kg/ha. Introduction of single cross hybrids, the productivity further increased to 7.0 t/ha and total nutrient removal has also increased to 420 kg/ha.
maize production still remained untreated with fertilisers. The extent of area was up to 90 % especially in areas where farmers are not sure to harvest their crop due to abiotic stresses, particularly during monsoon season. Besides, the current nutrient use in the high input maize systems indicates imbalance plant nutrition with very high use of N and less use of P and negligible use of K fertilisers and micro nutrients. This has led to nutrient imbalances in soils and lower nutrient use efficiency and economic profitability. This warrants adequate and balanced use of plant nutrients not only for specific farm and ecology but also in production systems using fertiliser best management practices adapted to local situations and farm typologies to achieve better efficiency and nutrient stewardship. Nutrient Response of Maize
In several states of the country particularly hill ecologies (North Eastern Himalayas, Uttarakhand, Himachal Pradesh) and rainfed and tribal states (Madhya Pradesh, Chhattisgarh, Rajasthan, Orissa, and West Bengal), large area under
While managing plant nutrients in maize systems, nitrogen (N), phosphorus (P), and potassium (K) remain the major ones for increased and sustained productivity. However, cultivation
Figure 4 – Potential, attainable and actual yields and management yield gaps under different ecologies across South Asia
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Indian Journal of Fertilisers, April 2013
Table 1 – Major nutrient removal from the soil by the maize plant Plant part Yield (t/ha) Nutrient extraction (kg/ha) N P K Ca Mg
Total Zn
Traditional cultivars Grain yield
1.0
25
6
15
3.0
2.0
0.023
51.0
Stover
1.5
15
3
18
4.5
3.0
0.040
43.5
Total
2.5
40
9
33
7.5
5.0
0.063
94.5
Grain yield
4.0
63
12
30
8.0
6.0
0.093
119.1
Stover
4.0
37
6
38
10.0
8.0
0.108
99.1
Total
8.0
100
18
68
18.0
14.0
0.201
218.2
Grain yield
7.0
128
20
37
14.0
11.0
0.163
210.2
Stover
7.0
72
14
93
17.0
13.0
0.189
209.2
14.0
200
34
130
31.0
24.0
0.352
419.4
Improved cultivars
Hybrid cultivars
Total Source: (41).
of high yielding maize systems will likely exacerbate the problem of secondary and micronutrient deficiencies, not only because larger amounts are removed, but also because the application of large amounts of N, P, and K to achieve higher yield targets often stimulates the deficiency of secondary and micronutrients (17). However, for determining right rates of nutrients, information on crop yield response to fertiliser application, agronomic efficiency and return on investment (ROI) to fertiliser application is also essential. Soils of the major maize growing areas in India are inherently low in soil organic matter and nitrogen is the major limiting plant nutrient, with N availability being routinely supplemented through application of fertilisers. Though the yield increase in maize due to N fertilisation was substantial (92%), the average agronomic efficiency of N (kg grain kg-1 N) in maize was only 12.5 (28), indicating low N use efficiency. Satyanarayana et al. (32) reported variable maize yield response to N fertiliser application, ranging from 400-5160 kg ha-1 with an average response of 2154 kg ha-1. Though N plays an important role in governing the yield of crops, Indian Journal of Fertilisers, April 2013
lack of awareness on improved strategies of N management, coupled with relatively lower prices of N fertilisers (especially urea), encourages imbalanced use by farmers. Therefore, N management strategies that consider the yield response, agronomic efficiency of N (AEN), coupled with appropriate timing and splitting, may be used not only for minimizing the losses of N from agricultural fields but also for increasing the yield and profitability from N use. A recent study (3) reported that increasing N levels from 130 to 390 kg N ha-1 resulted in increasing maize yield from 4.3 to 9.02 t ha-1 in the maizewheat cropping system (MWCS) of northern Karnataka. However, they also reported that in addition to crop response, AEN and ROI also need to be considered while deciding N application rate in the MWCS. P response is highly variable and is influenced by soil characteristics and growing environment of the crop. P application rate, therefore, must be based on expected response of a particular location. An average maize P response of 853 kg ha-1 across 36 locations in Bihar and West Bengal was reported (14),
which also indicated that the average P responses were higher in winter maize (1070 kg/ha) than in spring maize (513 kg/ha). However, P application based on yield response alone does not take into account the nutrient removal by crops where response is low or negligible. In such scenarios, nutrient removal by the crop would not be replenished adequately by external application, which may lead to nutrient mining and decline in soil fertility. One way to counter that would be to apply a maintenance dose that replenishes part of the nutrient exported out of the field with harvested crop part (grain and straw). This will ensure that soil fertility levels that can support intensive production systems are maintained. Finally, management of P fertiliser for maize systems must take account of residue and organic amendments applied to the soil. Indian soils, despite often having relatively large total K content, resulted in variable yield and economic loss to the farmers with skipping application of K. Longterm use of N and P in the absence of K illustrates the seriousness of nutrient imbalance of a region. Li 85
et al. (19) demonstrated the effect of K fertilisation on maize production within a region that has typically relied on N and P alone. They reported that balanced use of N, P, and K fertiliser generated an average yield increase of 1.2 t/ha and improved farm income by USD 300/ha when compared to common farmer practice. Grain yield response to fertiliser K is highly variable and is influenced by soil, crop and management factors. Majumdar et al. (21) reported that the average yield loss of maize in Indo-Gangetic Plains due to omission of K application was 700 kg ha-1. These observations were in contrary to the general perception that omitting potash for a season will not adversely affect maize production in the country. The results also demonstrate clearly the low K supply levels of most maize growing soils in India. Therefore, improved K management will have great potential for improving the overall productivity of maize systems in India. A systematic approach of nutrient management (22) indicated that N, P, K, and Zn were the most limiting nutrients for maize growth in Tamil Nadu and relative yields were 57, 63, 71, and 75% of the optimum when N, P, K, and Zn were omitted. Also, maize yields and responses to applied nutrients varies considerably across farmer fields, mainly because of small and marginal landholdings that result in high variability in soil nutrient availability over small distances (33). The generally high variability in maize nutrient responses across fields and establishment practices suggests that spatial and temporal differences of nutrient availability needs to be accounted for while formulating nutrient management strategies in maize. Besides, large variability in crop response to all nutrients indicates the need to develop fertiliser recommendation tools that consider more than just a soil test (19). In other words, bestbet approaches for nutrient 86
management like site-specific nutrient management and decision support tools like Nutrient Expert for Hybrid Maize, based on realistic estimates of indigenous nutrient supply and nutrient requirements for a targeted crop yield for individual farmers’ fields, will be required to improve yield and nutrient use efficiencies in maize production systems. Fertiliser Best Management Practices for Maize Nutrient management in multiple cropping systems is a complex process. Maize and maize-based systems involving cereals, extract large amounts of mineral nutrients from the soil due to large grain and stover yields. Proper nutrient management of exhaustive maizebased systems should aim to supply fertilisers adequate for the demand of the component crops and apply in ways that minimize loss and maximize the efficiency of use. The amount of fertiliser required depends on many factors including the indigenous supply of each nutrient which can be of appreciable quantities (5). Phosphorus inputs from irrigation and rain waters are negligible but 1,000 mm irrigation through surface water may provide up to 30 kg K ha-1 yr-1 (8, 9) and up to 1,100 kg S ha -1 yr -1 (27). In Rice-Maize (RM) systems, K inputs may be much larger than 30 kg ha-1 where groundwater is used. Thus, emphasis must be upon the nutrient requirements for target yields and nutrient supply by integrated use of indigenous sources, soil organic matter (SOM), farm yard manure (FYM), composts, crop residues, and increasingly, fertilisers to achieve and sustain high yields and nutrient use efficiencies of intensive maize-based systems. Fertiliser is the dominant source of nutrients and is required to increase yield of crops but should be applied in such a quantity that it becomes profitable and will have least adverse effect on environment.
Improving our understanding of uptake timing and rates, partitioning, and remobilization of nutrients by maize plants provides opportunities to optimize fertiliser rates, sources, and application timings. Optimizing nutrient management in maize systems includes using the right source at the right rate, at the right time, and at the right place - the 4R approach (4). While developing fertiliser recommendations for maize, two major aspects of plant nutrition are important to understand for managing high yielding maize production systems. This includes: 1) the amount of a given mineral nutrient that needs to be acquired by the plant during the growing season, referred to as “total nutrient uptake,” or nutrients required for production, and 2) the amount of the nutrient transported out of the field with grain and straw/stover, referred to as “removed with harvested product”. Providing the nutrients as and when required by the crop and replenishing the exported nutrient out the field with harvested products ensures sustainability of production systems. Further improvement of fertility practices require matching in-season nutrient uptake with availability, a component of the right source, which is interconnected with the other components of 4R Principle. The maximum rate of nutrient uptake coincides with the greatest period of dry matter accumulation during vegetative growth for most nutrients. Unlike the other nutrients, P, S, and Zn accumulation are greater during grain-filling than vegetative growth; therefore, season-long supply is critical for balanced crop nutrition. Similarly, micronutrients demonstrate more narrow periods of nutrient uptake than macronutrients, especially Zn and B. Therefore, fertiliser sources that supply nutrients at the rate and time that match maize nutritional needs are critical for optimizing nutrient use Indian Journal of Fertilisers, April 2013
efficiencies. Effectively minimizing nutrient stress requires matching nutrient supply with plant needs, especially in high-yielding conditions. Sulphur and N, for example, are susceptible to similar environmental challenges in the overall goal of improving nutrient availability and uptake. However, the timing of N uptake in comparison to S is surprisingly different (2), suggesting practices that are effective for one but may not improve uptake of the other. In case of Nitrogen, two-thirds of the total plant uptake is acquired by VT/R1 crop physiological stage of maize, whereas S accumulation is greater during grain-filling stages with more than one-half of S uptake occurring after VT/R1. Similarly, potassium, like N, accumulates two-thirds of total uptake by VT/R1 and greater than one-half of total P uptake occurs after VT/R1 (2), suggesting that season-long supply of P and S is critical for maize nutrition while the majority of K and N uptake occurs during vegetative growth. Unlike N, P, K, and S, which have a relatively constant rate of uptake, micronutrients exhibit more intricate uptake patterns. Uptake of Zn and B, for example, begins in the early vegetative stages and reaches a plateau at VT/R1 stage of the crop. Thereafter, Zn exhibits a constant uptake rate similar to that of P and S, while B uptake follows a major sigmoidal uptake phase concluding around R5 stage of maize. Zinc and B follows shorter periods of more intense uptake in comparison to macronutrients. Late vegetative and reproductive growth, constituting only onethird of the growing season, accounts for as much as 71% of Zn uptake by maize. A similar trend is also noticed for B where, as much as 65% of B uptake occurred over only one-fifth of the growing season (2). This also indicates that matching micronutrient needs of maize in high- yielding conditions clearly requires supplying nutrient sources and rates that can Indian Journal of Fertilisers, April 2013
meet crop needs during key growth stages. Therefore, the 4R approach (right source, right time, right amount and right place) holds merit not only attaining higher yields but efficiency, profitability and environmental stewardship.
different combinations and levels of organic and fertiliser sources of nutrients {without organic manure (O0) and application of FYM @ 6 t/ ha (O1) with four levels of fertiliser nutrients i.e., 100:40:30 (N 1 ), 150:60:40 (N2), 187:75:50 (N3) and 225:90:60 N: P2O5: K2O kg/ha (N4)}, showed that application of FYM @ 6 t/ha at N4 level resulted in highest grain yield during both the years which was at par with sole fertiliser application at N3 level in the second year. The application of O1 N4 resulted in 21.5 & 25.2; 14.4 &13.6; 9.2 & 11.6; 20.0 & 16.8 and 11.1 & 9.0 per cent increase over O0N1 , O0N2 , O0N3 , O1N1 , and O1N2 in the pooled grain yield of all the locations during 2007 and 2008, respectively. Pooled analysis of nutrient productivity across locations during both the years showed that it was highest with the application of O0 N1 treatment as the application level produced maximum yield response often observed at the lower part of yield response curves.
Integrated Nutrient Management Including Crop Residues Intensified and multiple cropping systems require judicious application of fertiliser, organic and bio-fertilisers for yield sustainability and improved soil health. Integrated plant nutrient supply (IPNS) system encompasses a combined use of different sources of plant nutrients for maintaining and improving the soil fertility for sustainable crop production without degrading the soil resource on long-term basis. It relies on a combined use of organic manures including green manures, recycling of crop residues, biofertilisers, vermicompost and a judicious and need based use of fertilisers. A summary of multilocation trials on integrated nutrient management in maize (16) under partially irrigated conditions (Table 2), comprising of
While managing maize residues in IPNS, it is important to understand nutrient distribution within the maize crop. Of the total nutrient
Table 2 – Effect of integrated nutrient management on yield and nutrient productivity (kg/ha) of quality protein maize in different agro-ecologies (pooled data of 7 locations across different ecologies in India) Treatment
Yield (kg/ha)
Nutrient productivity (kg grain/kg nutrient applied)
O0N 1
2007 4226f
O0N 2
4735e
4930de
20.8b
20.5b
O0N 3
5136cd
5173cd
17.7bcd
16.8c
O0N 4
b
bc
cd
14.7cd
bc
20.1b
5482
ef
2008 4395f
5512
2008 26.1a
15.4
ef
O1N 1
4482
O1N 2
5069d
5333c
16.6bcd
16.6c
O1N 3
bc
ab
14.9
d
14.6cd
13.5
d
13.2d
O1N 4
5433
5839
a
4766
2007 28.1a
5745
6099
19.9
a
p value
